Purity of nuclear envelopes isolated from rat liver. (A) Reactivity of PBC sera (s) as detected by IIF on HeLa cells and nuclei isolated from rat liver. Note the cytoplasmic pattern of fluorescence and the absence of staining on nuclei. The same PBC sera were tested (B) for anti-mitochondrial autoantibodies by dot blotting (mitochondria profile blot, Alphadia Diagnostic Products, Wavre, Belgium) and (C) on nuclear envelopes from rat liver by immunoblotting. Note for all sera the presence of anti-mitochondrial autoantibodies and the absence of reactivity on nuclear envelopes.